[CH2:1]([O:3][C:4]1[C:5]2[N:6]([N:14]=[CH:15][C:16]=2[C:17]([O:19]CC)=[O:18])[C:7]2[C:12]([N:13]=1)=[CH:11][CH:10]=[CH:9][CH:8]=2)[CH3:2].[OH-].[Na+]>C(O)C>[CH2:1]([O:3][C:4]1[C:5]2[N:6]([N:14]=[CH:15][C:16]=2[C:17]([OH:19])=[O:18])[C:7]2[C:12]([N:13]=1)=[CH:11][CH:10]=[CH:9][CH:8]=2)[CH3:2]To a solution of 2.85 g. of 4-ethoxypyrazolo[1,5-a]quinoxaline-3-carboxylic acid, ethyl ester in hot ethanol, there is added 10 ml. of 10% aqueous sodium hydroxide and the mixture refluxed for 2 hours. The mixture is concentrated under reduced pressure and the residue dissolved in water. The solution is filtered and neutralized with dilute hydrochloric acid. The precipitated 4-ethoxypyrazolo[1,5-a]quinoxaline-3-carboxylic acid is filtered and washed with a small amount of cold water. The product is crystallized from ethanol.
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